Boletín de la Sociedad Española de Cerámica y Vidrio (Aug 2000)
Failure mechanisms of aluminium foams under compressive loads
Abstract
The purpose of this paper is the investigation of the major failure mechanisms of aluminium foams, which were obtained by powder metallurgy route, under compressive loads. The study was focused on two commonly aluminium alloys AlMg1Si or A 6061 and AlSi12. Due to the fact that the failure mechanisms strongly depend on the density and the macrostructural properties of the material, the mechanical properties always have to be correlated to the structural properties. Therefore, macrostructural investigations were used as a basis to establish the correlation between structural and mechanical properties. This was done with a commercially available image analysis system. The average cell size, the cell size distribution and the cell density (number of cells/area) were obtained. In order to evaluate the influence of foaming direction on the cell morphology, some cross sections parallel to the foaming direction were prepared. For the characterization of the mechanical compression properties the compressive or upper yield strength (UYS), the densification strain (eD), the energy absorption (Ea) and the efficiency (Eff) were obtained. Furthermore, the failure behavior of the samples was in-situ observed with a digital video camera and continuously recorded during the test.<br><br>El objetivo de este estudio es investigar los principales mecanismos de fallo de espumas de aluminio sometidas a cargas de compresión. Las espumas metálicas fueron obtenidas mediante el proceso pulvimetalúrgico, utilizándose como materia prima dos aleaciones comerciales AlMg1Si o A 6061 y AlSi12. Debido a que los mecanismos de fallo en este tipo de materiales depende fuertemente de la densidad y las características macroestructurales del material, en este estudio se busca correlacionar las propiedades mecánicas con estas características. La macroestructura se caracterizó mediante análisis de imagen. El tamaño de celda promedio, la distribución de tamaño y la densidad de celdas (número de celdas por área) fueron obtenidas en diferentes secciones transversales paralelas a la dirección de espumado. Mediante ensayos mecánicos de compresión se obtuvieron la resistencia a compresión o resistencia elástica superior (UYS), la deformación de densificación (eD), la energía absorbida (Ea) y la eficiencia (Eff). Los ensayos de compresión se grabaron mediante una cámara digital de vídeo realizándose su análisis posteriormente.
